Method and apparatus for processing sub-micron write head flare definition

ABSTRACT

A method and apparatus for processing sub-micron write head flare definition is provided. The method for processing a perpendicular magnetic head forms a portion of a perpendicular write head, where the portion of the write head includes a first pole layer, a coil layer, a second pole layer and a write pole, the method forms a portion of a magnetic read head adjacent to the portion of the perpendicular write head, where the portion of the read head includes a shield layer and a sensor, the method also laps the write pole concurrently with the sensor to define a flare position of the pole tip and to define a sensor height, where the flare position of the pole tip is defined in the same photo-lithography step as the back edge of the sensor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates in general to magnetic recording systems,and more particularly to magnetic recording systems having write headswith improved flare definition and method of its manufacture.

2. Description of the Related Art

Fixed magnetic storage systems are now commonplace as a mainnon-volatile storage in modern personal computers, workstations, andportable computers. Storage systems are now capable of storing gigabytequantities of digital data, even when implemented in portable computers.

As disk drive technology progresses, more data is compressed intosmaller areas. Increasing data density is dependent upon read/writeheads fabricated with smaller geometries capable of magnetizing orsensing the magnetization of correspondingly smaller areas on themagnetic disk. The advances in magnetic head technology has led to headsfabricated using processes similar to those used in the manufacture ofsemiconductor devices.

A typical disk drive is comprised of a magnetic recording medium in theform of a disk for storing information, and a magnetic read/write headfor reading or writing information on the disk. The disk rotates on aspindle controlled by a drive motor and the magnetic read/write head isattached to a slider supported above the disk by an actuator arm. Whenthe disk rotates at high speed a cushion of moving air is formed liftingthe air bearing surface (ABS) of the magnetic read/write head above thesurface of the disk.

The read portion of the head is typically formed using amagnetoresistive (MR) element including giant magnetoresistive heads incurrent in- and perpendicular- to plane configurations, and sensor usingtunneling current. This element is a layered structure with one or morelayers of material exhibiting the magnetoresistive effect. Theresistance of a magnetoresistive element changes when the element is inthe presence of a magnetic field. Data bits are stored on the disk assmall, magnetized region on the disk. As the disk passes by beneath thesurface of the magnetoresistive material in the read head, theresistance of the material changes and this change is sensed by the diskdrive control circuitry.

The write portion of a read/write head is typically fabricated using acoil embedded in an insulator between a top and bottom magnetic layer.The magnetic layers are arranged as a magnetic circuit, with pole tipsforming a magnetic gap at the air bearing surface of the head. When adata bit is to be written to the disk, the disk drive circuitry sendscurrent through the coil creating a magnetic flux. The magnetic layersprovide a path for the flux and a magnetic field generated at the poletips magnetizes a small portion of the magnetic disk, thereby storing adata bit on the disk.

The process for fabricating the write portion of a read/write headtypically uses processes that define the width of pole tips.Furthermore, write head flare, which is the area where the second polepiece begins to widen above the air bearing surface, is not well defineddue to limited capability of alignment in optical lithography. Becauseflare point placement directly affects the magnitude of the write fieldat the recording medium, inaccurate placement of the flare point canresult in non-functioning head. This situation is especially serious forperpendicular recording, since the required accuracy of the flareposition exceeds the processing tolerances, resulting in enormous yieldloss in head fabrication.

It can be seen therefore, that there is a need for a method of definingwrite head flare with high degree of accuracy.

SUMMARY OF THE INVENTION

To overcome the limitations in the prior art described above, and toovercome other limitations that will become apparent upon reading andunderstanding the present specification, the present invention disclosesa method for controlling write head flare in the process of fabricatingheads for perpendicular recording utilizing a side-by-side read/writegeometry.

The present invention solves the above-described problems by providing amethod for defining a perpendicular magnetic head with sub-micron writehead flare definition by simultaneously defining the write head flareand the back edge of the sensor in one optical lithography step. Then,using conventional method to lap to the target sensor stripe heightensures accuracy of the flare position of the write head.

A method for defining a perpendicular magnetic head according to anembodiment of the present invention includes forming a portion of theread and write head including the first shield layer, the read gap,first and second pole layers, and a coil layer, depositing the senorfilm on the surface only over the region of the read head, depositing afull-film shaping pole layer over the write head, defining the trackwidth of the sensor, patterning of a photoresist to define the pole tipof the write head including write track width and flare position, and atthe same time to define the back edge of the sensor, removing materialof the sensor and pole tip from the areas not covered by photoresist,completing the fabrication of the write and read head layers and lappingthe write pole concurrently with the sensor to define a flare positionof the pole tip and to define a sensor height with accurate positioningof write head flare.

In another embodiment of the present invention, a perpendicular magnetichead is provided. The perpendicular magnetic head includes aperpendicular write head comprising a first pole layer, a coil layer, asecond pole layer and a write pole having a pole tip layer and a surfacemerging with the second pole layer and a magnetic read head disposedadjacent to the perpendicular write head, wherein the magnetic read headcomprises a shield layer and a sensor, the sensor being formed in a sameplane as the pole tip layer, wherein the write pole and the magneticread head include a common lapped surface defining a flare position ofthe pole tip and a sensor height, wherein the flare position of the poletip is defined at the point where the pole tip and the second pole layermerge.

In another embodiment of the present invention, a magnetic storagesystem is provided. The magnetic storage system includes at least onemoveable magnetic storage medium, at least one read/write magnetic headdisposed adjacent the at least one moveable magnetic storage medium andan actuator assembly, coupled to the at least one read/write magneticread/write head, for moving the at least one magnetic read/write headrelative to the at least one moveable magnetic storage medium, whereinthe at least one read/write magnetic head includes a perpendicular writehead comprising a first pole layer, a coil layer, a second pole layerand a write pole having a pole tip layer and a surface merging with thesecond pole layer and a magnetic read head disposed adjacent to theperpendicular write head, wherein the magnetic read head comprises ashield layer and a sensor, the sensor being formed in a same plane asthe pole tip layer, wherein the write pole and the magnetic read headinclude a common lapped surface defining a flare position of the poletip and a sensor height, wherein the flare position of the pole tip isdefined at the point where the pole tip and the second pole layer merge.

These and various other advantages and features of novelty whichcharacterize the invention are pointed out with particularity in theclaims annexed hereto and form a part hereof. However, for a betterunderstanding of the invention, its advantages, and the objects obtainedby its use, reference should be made to the drawings which form afurther part hereof, and to accompanying descriptive matter, in whichthere are illustrated and described specific examples of an apparatus inaccordance with the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 is a flowchart of a method for fabricating read/write heads usinga precise method to define write head pole tip flare according to anembodiment of the present invention;

FIG. 2 is a plan view of an exemplary prior art magnetic disk drive;

FIG. 3 is an elevation view of the prior art magnetic disk drive whereinmultiple disks and magnetic heads are employed;

FIG. 4 is an isometric illustration of an exemplary prior art suspensionsystem for supporting the slider and magnetic head;

FIG. 5 is an ABS view of the magnetic head;

FIG. 6 is a cross-sectional view of a perpendicular write head that canbe used in accordance with embodiments of the invention;

FIG. 7 is an ABS view of a perpendicular write head side-by-side with aread head in accordance with an embodiment of the invention;

FIG. 8 is an isometric view of a second pole piece of FIG. 7, whichincludes a bottom pole piece and a top pole tip layer in accordance withan embodiment of the invention;

FIG. 9 is a top view of FIG. 8; and

FIGS. 10 a-d show cross-sectional and wafer views of the fabrication ofa perpendicular write head with improved flare definition according toan embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description of the exemplary embodiment, reference ismade to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration the specific embodiment in whichthe invention may be practiced. It is to be understood that otherembodiments may be utilized as structural changes may be made withoutdeparting from the scope of the present invention.

In embodiment of the present invention methods for processing aside-by-side read/write head in order to achieve a high degree of writehead flare precision is provided. The point where the pole tip and headmerge is called the flare point because the pole tip begins to widen asit recesses into the head. Similarly, a flare point can be described asthe area where the second pole piece begins to widen (flare) above theair bearing surface at the bottom of the yoke. Thus, achieving a highprecision of write head flare involves precisely defining the flarepoint situated above the air bearing surface.

Accurately defining the flare point of a write head is an importantdesign parameter. Magnetic flux decays as it travels down the length ofthe second pole tip. Thus, more flux will reach the recording media ifthe length of the second pole tip is made short. Placing a flare pointnear the air bearing surface of a write head can lead to the ability tomake the second pole tip shorter and enable more flux to reach therecording media thereby optimizing performance. In the past it has beendifficult to locate the flare point closer to the ABS than 0.5-1 μm dueto fabrication problems associated with the pole tip.

FIG. 1 is a flowchart 10 of a method for fabricating read/write headsaccording to an embodiment of the present invention. In FIG. 1, aportion of the read and write head including the first shield layer S1,the read gap, first and second pole layers, and a coil layer are formed12. Then, the senor film is deposited on the surface only over theregion of the read head 13. A full-film shaping pole layer is deposistedover the write head 14. The track width of the sensor is defined 15. Aphotoresist is used to define the pole tip of the write head includingwrite track width and flare position, and at the same time to define theback edge of the sensor 16. Material of the sensor and pole tip isremoved from the areas not covered by photoresist 17. The fabrication ofthe write and read head layers is completed 18. The write pole is lappedconcurrently with the sensor to define a flare position of the pole tipand to define a sensor height with accurate positioning of write headflare 19.

Side-by-side read/write heads fabricated in accordance with the presentinvention can be incorporated into magnetic disk drives. FIGS. 2-4illustrate an exemplary magnetic disk drive 30 where like referencenumerals designate like or similar parts throughout the several views.The drive 30 includes a spindle 32 that supports and rotates a magneticdisk 34. The spindle 32 is rotated by a spindle motor 36 that iscontrolled by a motor controller 38. A slider 42 has a combinedread/write magnetic head 40 and is supported by a suspension 44 andactuator arm 46 that is rotatably positioned by an actuator 47. Aplurality of disks, sliders and suspensions may be employed in a largecapacity direct access storage device (DASD) as shown in FIG. 3. Thesuspension 44 and actuator arm 46 are moved by the actuator 47 toposition the slider 42 so that the magnetic head 40 is in a transducingrelationship with a surface of the magnetic disk 34. First and secondsolder connections 104 and 106 connect leads from the sensor 40 to leads122 and 123, respectively, on suspension 44 and third and fourth solderconnections 116 and 118 connect to the write coil (not shown) to leads128 and 129, respectively, on suspension 44.

When the spindle motor 36 rotates the disk 34 the slider is supported ona thin (typically, 0.05 μm) cushion of air (air bearing) between thesurface of the disk 34 and the air bearing surface (ABS) 48. Themagnetic head 40 may then be employed for writing information tomultiple circular tracks on the surface of the disk 34, as well as forreading information therefrom. Processing circuitry 50 exchangessignals, representing such information, with the head 40, providesspindle motor drive signals for rotating the magnetic disk 34, andprovides control signals to the actuator for moving the slider tovarious tracks. In FIG. 4 the slider 42 is shown mounted to a suspension44. The components described hereinabove may be mounted on a frame 54 ofa housing 55, as shown in FIG. 3.

FIG. 5 is an ABS view of the slider 42 and the magnetic head 40. Theslider has a center rail 56 that supports the magnetic head 40, and siderails 58 and 60. The rails 56, 58 and 60 extend from a cross rail 62.With respect to rotation of the magnetic disk 34, the cross rail 62 isat a leading edge 64 of the slider and the magnetic head 40 is at atrailing edge 66 of the slider.

FIG. 6 is a cross-sectional view of a write head that can beincorporated in side-by-side read/write heads in accordance with thepresent invention. The write head 600 includes first and second polepieces 601 and 602 which extend from the ABS to back gap portions 604and 606 which are recessed in the head and which are magneticallyconnected to a back gap layer 608. The second pole piece 602 includes aleading edge tapered pole tip layer (PT layer) 612. Located between thefirst and second pole pieces 600 and 602 is an insulation layer 614which extends from the ABS to the back gap layer 608 and has embeddedtherein at least one write coil layer 620. A bottom portion ofinsulation layer 614 insulates the write coil from the first pole piece601.

In accordance with the present invention, FIG. 7 illustrates aside-by-side write/read head as viewed from the air bearing surface. Theread head sensor 730 is sandwiched between nonmagnetic electricallynonconductive first and second read gap layers 760 and 780, and the readgap layers are sandwiched between ferromagnetic first (S1) and second(S2) shield layers 710 and 720. In response to external magnetic fields,the resistance of the sensor 730 changes. The write head of FIG. 7 is analternate view of the write head depicted in FIG. 6. The write headincludes first and second pole pieces 601 and 602, pole tip 612 and coil620.

As shown in FIGS. 8 and 9, the second pole piece 602 includes the bottomsecond pole piece (P2) layer 610 and the top ferromagnetic pole tip (PT)layer 612. The layers 610 and 612 have flare points 611 and 613 wherethe layers first commence to extend laterally outwardly after the ABS.The pole tip layer 612 has a pole tip 622 and a yoke, which is, locatedbetween the pole tip 622 and the back gap 608. The width of the pole tip622 is the track width (TW) of the recording head.

In a side-by-side configuration, a read/write head can be fabricated ina variety of ways. FIGS. 10 a-d show cross-sectional and wafer views ofthe fabrication of a perpendicular write head 1000 with improved flaredefinition according to an embodiment of the present invention. In FIGS.10 a-d, the left portion is the cross-sectional view indicated by thedashed lines in the wafer view shown on the right.

In FIG. 10 a, a portion of the read and write head is formed, includingthe first shield layer S1 1010 and the read gap G1, and the portion ofthe write head including first and second pole layers 1030, 1040, and acoil layer 1035 as shown in FIG. 10 a. The top of the write head layerP2 is at the same level as the read gap G1 of the read head. Then, thesenor GMR or TMR film is deposited on the surface, but is left only overthe region of the read head. This is done by either lift-off techniqueor by ion-milling the sensor material in the area of the write head.Then, using a lift-off technique, the full-film shaping pole layer 1050is deposited over the write head. The material used for shaping layer isCoFe or laminated CoFe, or any other pole tip layer material, preferablyof magnetic material with high saturation moment. Then, the track widthof the sensor 1020 is defined using standard techniques for read headprocessing, including electrical connection leads and hard biasstabilization layer (not shown).

The right side of FIG. 10 b shows the patterning of a photoresist usingthe same lithographic step described above. In FIG. 10 b, thephotoresist 1060 is the unshaded area and the shaded area 1062represents the wafer surface with the photoresist removed. This stepdefines the pole tip of the write head, including write track width andflare position, and at the same time defines the back edge of the sensor1020. Using ion milling, material of the sensor 1020 and pole tip 1050is removed from the areas not covered by photoresist 1060 defined in theprevious step. After milling is completed, the sensor stripe height andthe write poles are defined. Referring to FIG. 10 c, the wafer portionof head fabrication is then concluded by depositing second sensor gapG2, which is topped by the second shield S2 over the read head.

FIG. 10 d shows the lapping step. Since the sensor stripe 1020 and thewrite pole 1050 are both defined at the same lithographic step, theposition of write pole flare 1064 is defined with unprecedented accuracywith respect to the senor back edge 1068. Other conventional steps usedin head processing can be used to complete formation of the head.Defining the pole tip layer 1050 in the same plane as the sensor layer1020 allows for accurate positioning of write head flare 1064 because inthe lapping step, tolerances within 20 nm can be achieved for currentprocesses, and a 5 nm tolerance can be achieved in single sliderlapping.

The foregoing description of the exemplary embodiment of the inventionhas been presented for the purposes of illustration and description. Itis not intended to be exhaustive or to limit the invention to theprecise form disclosed. Many modifications and variations are possiblein light of the above teaching. It is intended that the scope of theinvention be limited not with this detailed description, but rather bythe claims appended hereto.

1. A method for defining a perpendicular magnetic head, comprising:forming a portion of the read and write head including the first shieldlayer, the read gap, first and second pole layers, and a coil layer;depositing the senor film on the surface only over the region of theread head; depositing a full-film shaping pole layer over the writehead; defining the track width of the sensor; patterning of aphotoresist to define the pole tip of the write head including writetrack width and flare position, and at the same time to define the backedge of the sensor; removing material of the sensor and pole tip fromthe areas not covered by photoresist; completing the fabrication of thewrite and read head layers; and lapping the write pole concurrently withthe sensor to define a flare position of the pole tip and to define asensor height with accurate positioning of write head flare.
 2. Themethod of claim 1, wherein lapping the write pole to define the flareposition of the pole tip concurrently with the sensor to define a sensorheight comprises lapping the write pole to achieve a flare in a range of10-500 nm.
 3. The method of claim 2, wherein lapping the write pole todefine the flare position of the pole tip concurrently with the sensorto define a sensor height is performed to an accuracy of at or about1-20 nm.
 4. The method of claim 1, wherein the depositing the senor filmis performed by either lift-off technique or by ion-milling the sensormaterial in the area of the write head.
 5. The method of claim 1,wherein the depositing a full-film shaping pole layer over the writehead is performed using a lift-off technique.
 6. The method of claim 1,the shaping layer comprises CoFe or laminated CoFe.
 7. The method ofclaim 1, wherein the shaping layer comprises pole tip layer magneticmaterial having a high saturation moment.
 8. The method of claim 1,wherein the patterning of a photoresist uses a lithographic step usedfor depositing a full-film shaping pole layer over the write head anddefining the track width of the sensor.
 9. The method of claim 1,wherein the removing material of the sensor and pole tip comprises usingion milling.
 10. The method of claim 1, wherein the completing thefabrication of the write and read head layers comprises depositingsecond sensor gap G2 topped by the second shield S2 over the read head.11. A perpendicular magnetic head, comprising: a perpendicular writehead comprising a first pole layer, a coil layer, a second pole layerand a write pole having a pole tip layer and a surface merging with thesecond pole layer; and a magnetic read head disposed adjacent to theperpendicular write head, wherein the magnetic read head comprises ashield layer and a sensor, the sensor being formed in a same plane asthe pole tip layer; wherein the write pole and the magnetic read headinclude a common lapped surface defining a flare position of the poletip and a sensor height, wherein the flare position of the pole tip isdefined at the point where the pole tip and the second pole layer merge.12. The perpendicular magnetic head of claim 11, wherein the write polecomprises a flare of up to 100 nm.
 13. The perpendicular magnetic headof claim 11, wherein the magnetic read head comprises a sensor heighthaving a tolerance of substantially 20 nm.
 14. A magnetic storagesystem, comprising: at least one moveable magnetic storage medium; atleast one read/write magnetic head disposed adjacent the at least onemoveable magnetic storage medium; and an actuator assembly, coupled tothe at least one read/write magnetic read/write head, for moving the atleast one magnetic read/write head relative to the at least one moveablemagnetic storage medium; wherein the at least one read/write magnetichead comprises: a perpendicular write head comprising a first polelayer, a coil layer, a second pole layer and a write pole having a poletip layer and a surface merging with the second pole layer; and amagnetic read head disposed adjacent to the perpendicular write head,wherein the magnetic read head comprises a shield layer and a sensor,the sensor being formed in a same plane as the pole tip layer; whereinthe write pole and the magnetic read head include a common lappedsurface defining a flare position of the pole tip and a sensor height,wherein the flare position of the pole tip is defined at the point wherethe pole tip and the second pole layer merge.
 15. The magnetic storagesystem of claim 14, wherein the write pole comprises a flare of up to100 nm.
 16. The magnetic storage system of claim 14, wherein themagnetic read head comprises a sensor height having a tolerance ofsubstantially 20 nm.